Icy weather could be help with Candlewood Lake weed problem

January 2, 2018 GMT

The freezing temperatures that have gripped the region for more than a week could bode well for those hoping Candlewood Lake will be less infested next summer with Eurasian watermilfoil.

For years, FirstLight Power Resources has lowered water levels over the winter in an effort to expose parts of the lakebed to the cold and kill the invasive plant, which has long been a nuisance for swimmers and boaters.

“Overall this weather is very encouraging,” said Greg Bugbee, who oversees the Invasive Aquatic Plant Program for the Connecticut Agricultural Experiment Station.

Temperatures below 27 degrees Fahrenheit generally are low enough to kill the weed. But temperature isn’t the only factor: The sediment must also be dry and the milfoil exposed to the air.

“Anything still covered by water is not going to be affected,” Bugbee said.

Snow acts as an insulator, Bugbee added. It might be minus 30 degrees outside, but the ground underneath the snow could be much warmer.


“A lot will have to deal with the snow cover,” Bugbee said. “It’s perfect conditions if it’s little or no snow.”

Meteorologists are still studying the models to determine how much snow is likely with storm predicted for Thursday.

The last time temperatures were above freezing in the Danbury area was on Christmas Day, when the high reached 37. Since then temperatures have ranged from lows below zero to highs in the teens or low 20s.

Danbury set records on Monday, with a low of -1 and a high of 15 degrees.

Subfreezing temperatures are expected to linger for the next few days too, prompting Gov. Dannel P. Malloy to extend the state’s Severe Cold Weather protocol through 5 p.m. Monday.

Danbury’s warmest temperature this week will be 26 degrees on Wednesday before dropping to a high of 9 degrees on Friday and 7 degrees on Saturday, according to the National Weather Service.

FirstLight varies the amount of water removed from the lake during the winter during what is called the “drawdown,” from several feet in a shallow drawdown to as many as 10 in a deep one.

FirstLight began drawing down the lake in mid-December and reached the target depth — between five and seven feet lower than normal summer levels — last Friday, said Len Greene, a FirstLight spokesman. He said he was unsure how long it takes for the sediment to dry.

The lake will return to the recreational depths by the opening of fishing season in early April.

Drawdown plans are created and approved by the Technical Drawdown Committee, which includes representatives from the Candlewood Lake Authority, U.S. Fish and Wildlife Service and the Connecticut Department of Energy and Environmental Protection.

”We do believe that the extreme cold weather will contribute to a successful drawdown and help to mitigate milfoil this summer,” Greene said.


The least acreage of milfoil Bugbee has seen in the past decade came in 2007, following a deep drawdown, with about 230 acres infested. Recent summers following shallow drawdowns have left about 500 acres, he said.

He expects the milfoil coverage next summer to be somewhere in between because the lake was seven feet lower than usual as of Tuesday morning, midway between shallow and deep drawdown levels.

Grass carp released into the lake by the Candlewood Lake Authority to eat the milfoil will also affect the acreage, though he said it’s too soon to tell by how much.

”They put 8,000 or so carp in and soon they’ll have to start eating,” Bugbee said.; 203-731-3345